gms | German Medical Science

Age-related macular degeneration is a multi-factorial disease. The fluorophores that are the source of short-wavelength fundus autofluorescence (488 nm excitation) and that constitute the lipofuscin of retina are vitamin A-adducts (bisretinoids) that form from reactions of retinaldehyde with primary amine groups such as these moieties on phosphatidylethanolamine. These compounds form in photoreceptor cells and are transferred secondarily to retinal pigment epithelial (RPE) cells. Bisretinoid lipofuscin accumulates in RPE cells as a hallmark of aging, can trigger photodamage and can account for the deposition of the dicarbonyls that modify Bruch’s membrane. These features together with evidence that the photooxidative processes initiated by bisretinoid lipofuscin can explain links amongst AMD, sunlight exposure and antioxidant intake, suggest a relationship to AMD. Since photooxidation of bisretinoid leads to degradation of these fluorophores, reduction of short-wavelength fundus autofluorescence (qAF) in atrophic AMD, is consistent with a role for bisretinoids in the pathogenic mechanisms of AMD.